Scientists have found the earliest copy of the Gioconda, the most famous smile in the world. In fact, it's so early that it was done by an apprentice at da Vinci's studio, at the same time or shortly after the original was made.

This painting arrived to Spain in 1666, to the collection of the Real Alcazar. During all this time, it was thought to be just one of the many copies of the classic. Nobody knew who did it. Experts only knew that it was made in the first quarter of the XVI century.

The surprise came last year when, during the process of restoration, El Prado's researchers found out that this was not any copy, but the very first known copy, one of extreme importance. The restoration process was taking several months, as scientists were removing a thick layer of varnish that obscured the background.

Talking at a congress in the National Gallery, El Prado's researchers Ana González Mozo said that their analysis reveal that this copy was actually made in Leonardo's studio by one of his apprentices. The experts believe it was made by Andrea Salai, Leonardo's lover or Francesco Melzi.

Talking to Spanish newspaper El País, the experts have revealed that this copy may have been made at the very same time as the original was being painted, by the master's side. The original wood canvas is 77 X 53 centimeters. The copy is 76 X 57. According to El Prado, several radiological and photographic studies have found new discoveries that may change the interpretation of the famous painting, as well as our understanding on how it was painted.

The restoration work of the Prado painting isn't yet complete. The picture should be fully restored by March, when it will go on exhibition in the Louvre in Paris from March 29 to June 25. Reportedly, it will be displayed next to the original. [El País and El Mundo—In Spanish]